body{
    margin: 0;
}
#div1 {
    height: 100px;
    background-color: black;
    color: #fff;
    font-size: 30px;
    text-align: center;
    padding-top: 40px;
}

#div3 {
    background-color: black;
    color: #fff;
    font-size: 20px;
    text-align: center;
    padding: 20px 0;
}
#left {
    width: 25%;
    height: 500px;
    background-color: #E5E5E5;
    float: left;
}

#right{
    width: 75%;
    float: left;
}
.menu {
    list-style-type: none;
    padding: 0;
}
.menu a {
    text-decoration: none;
    color: #000;
    padding: 10px 0px;
    display: block;
}
.menu li {
    padding: 0px 20px;
}
.menu li:hover{
    background-color: #ddd;
}

.content{
    padding: 20px;
}